Guide and retaining means for punch mechanism



A9151 1 63 A. FERREN 3,083,604

GUIDE AND RETAINING MEANS FOR PUNCH MECHANISM Filed July 7, 1959 INVENTOR ARTHUR L. FERREN FIG. 5 BY ATTORNEY United States Patent 3,983,ti4 AND ERETAL HNG BEANS FGR EUNCH ivlEfIEiANiSM Arthur L. Fen-en, Park Ridge, iii, assigns: to Teletype 'Cerporation, hicago, iii, a corporation of Delay/a: Filed Eariy '7, 1959, Ser. 825,599 4 Hair us. (Q3. 83635) This invention relates to the method of manufacturing a punch block assembly which utilizes a casting resin to form punch pin guiding and retaining apertures and the article of manufacture produced thereby.

Te etypewriter perforations typically employ a punch block assembly, of the type depicted in Patent No. 2,308,- 543, issued to A. H. Reiber on January 19, 1943, to make intelligence bearing perforations in a tape in the form of a code, such as the unit Baudot code. Since the perforations are intelligence bearing, the punch pins in such an assembly must respond quickly and accurately so as to faithfully reproduce the intelligence coming into the perforator. Such punch pin response necessary requires that the method of manufacture used to produce the punch pin assembly meet very exacting manufacturing requirements. The principal difficulty involved in the manufac ture of such a punch block assembly is the forming of the apertures which guide and retain the punch pins. To insure quick response of the punch pins, and accurate positioning of the perforations produced thereby, the pins must be closely retained by the apertures so as to prevent any lateral movement of the pins during a punching op eration yet the apertures must be sufiicien-tly large so as not to bind the punch pin during its punching movement. Previously, such pin assemblies were manufactured by securing a guide plate above and below a generally inverted U-shaped casting. A die plate was then secured to the upper guide plate and the punch pin guiding and retaining apertures were drilled simultaneously through each of the three plates. To meet the aforementioned exact manufacturing requirements, each punch pin was then individually lapped into its respective aperture. Obviously, such a customized method of manufacture was time consuming, tedious and extremely expensive.

It is an object of this invention to provide a method of manufacturing a punch block assembly which is inexpensive and easy to practice.

A further object of the invention is to provide a method of manufacturing a punch block assembly in which a casting resin is employed to provide punch pin guiding and retaining means.

A feature of the present invention is the forming of punch pin receiving slots in a punch block assembly by the crush grinding process.

Another feature of the present invention is the surrounding of a lubricant coated punch pin, disposed in a punch pin receiving slot formed in a die plate and punch block assembly, with a casting resin so as to provide punch pin retaining and guiding means.

A more complete understanding of the present invention may be obtained from the following detailed description of the method of manufacturing a punch block assembly when read in conjunction with the appended drawings in which:

FIG. 1 is an isometric view of a punch block and die plate, with the die plate displaced from the punch block;

FIG. 2 is an isometric view of the die plate secured to the punch block showing a plurality of punch pin receiving slots formed in the assembly, a portion of the die plate being broken away for clarity;

FIG. 3 is an elevatonal view showing punch pins being disposed within the slots formed in the die plate and punch block prior to a casting operation;

FIG. 4 is a cross sectional view taken along the line 4-4 in FIG. 3 in the direction of the arrows as viewed after the completion of the casting operation; and

FIG. 5 is a cross sectional view taken along the line 55 in FIG. 4 in the direction of the arrows.

Referring now to the drawings and more particularly to FIG. 1, there is shown a punch block 10 having a cavity 11 formed therein which serves as a die mold in a casting operation. Gpenings 12 and 13, leading into the cavity 11, are provided with counter sunk portions 14 and 15-, respectively, the purpose of which portions 'will be described in full infra. l-dso shown in FIG. 1 is a die plate 16 displaced from the punch block 10 preparatory to being secured to the punch block. A slot 17 is formed in the punch block 10 to provide a passageway between the punch block and the die plate for a web of material such as a strand of tape.

After the die plate 16 has been secured to the punch block 10 in a suitable manner, as by threaded fasteners 18, a plurality of punch pin receiving slots 19, as illustrated in FIG. 2, are formed simultaneously ,in the die plate 16 and punch block 10 by a crush grinding process.

The crush grinding process is Well known in the art and derive-s its name from the method used to dress or shape the periphery of a grinding wheel. The periphery of the grinding wheel is shaped by applying to the face of the wheel, under pressure, steel or cast iron rolls having the same profile as the indentations to be formed in a work piece. The pressure applied by the steel or iron rolls to the face of the grinding wheel crushes the abrasive grains from the bonding agent comprising the grinding wheel to produce the desired form. Thereafter the punch block and die-plate have the slots ground therein by the wheel, the surface of which has been dressed to the desired contour. t will be understood that the punch pin receiving slots can be formed in any conventional manner, the crush grinding process being set forth merely by way of example.

After the plurality of punch pin receiving slots have been formed in the assembly and the assembly has been cleaned with a suitable cleaning agent, the assembly is placed upon a suitable flat surface, such as the top of a work bench in a casting shop, with the surface of the punch block into which the countersunk portions 14- and 15 open, downward.

Preparatory to being placed in the slots 19, the punch pins 20 are cleaned, with a suitable cleaning agent, and coated with a suitable lubricant or mold release compound such as wax or silicone mold release compound. Typically, after being cleaned, the pins 26 are immersed in a solution of silicone mold release compound in an organic solvent. The pins are withdrawn from the solvent in a vertical position and allowed to dry while remaining in the vertical position. The pins 20 are then placed in the slots 19, as may be seen in FIG. 3, preferably such that the pin is midway between its upper and lower operating positions whereby the bow effect, introduced in the pins when they are moved upward into their punching positions, is minimized. It will 'be noted that the punch pins span the cavity 11 formed in the die block 10, extend through the die plate 16 and through the slots formed in the punch block above and below the cavity formed in the punch block.

An epoxy resin, such as for example, any of those disclosed in C-astan Patents 2,324,483 and 2,444,333, granted July 20, 1943, and June 29, 1948, respectively, Greenlee Patents 2,494,295 and 2,511,913, granted January 10, 1950, and June 20, 1950, respectively, and Bradley Patent 2,500,600, granted March 14, 1950, the disclosures of which are hereby incorporated by reference as if fully set forth herein, is poured into the cavity 11 to fill the cavity, the openings 12 and 13, countersunk portions 14 and 15 and to surround circumferentially the portions of 3 the punch pins spanning the cavity 11. The epoxy resin is prevented from flowing into the punch pin receiving slots 19 formed in the punch block 10' by .one of several methodswell known in the castingart such as filling the slots with plaster, a rubber-like substance or a suitably designed metal dam.

Epoxy resins are well known in 'the art and have a high order of utiIi-ty in a castingroperation, such as that employed in the present invention, due to their characteristics of permitting casting at low temperature. and,

under low pre'ssure, possessing good physical properties,

especially resistance to shock and abrasion, and possessing good chemical properties particularly as to low solubility in acids and organic solvents. I It will be notedthat the epoxy'resin described in the aforementioned patent is suggested merely byway of example, and that the present invention is not limited to the use of the particular resin disclosed'therein, but may be practiced with any-of a a number of epoxy resins which exhibit similar general char-- acteristics, -Accordingly, it is further noted that the present invention is not dependent upon the characteristics of I the particular epoxy resins incorporated herein byreference.

The epoxy resin filling the countersunk portions 14 and 15 will serve as retaining flanges to assure that'the bodyof resin will notrbec'ome dislodged from the cavity 11, due. to shock attendantthe operation-of the punch block assembly; should there be insufficient adhesive force between the resin and walls of the cavity'to retain the body of resin in the cavity.

Inspection'jof the resulting punch block assembly re- 7 veal-s that the punch pin guiding and retaining apertures- =forrned solely by the epoxy resin which-surrounds circumferentiallythe punch pins, 20, as shown in FIG. 5, willbe customized to fit each individual punch pin and will'obviatethe aforementioned time consuming and expensive. requirement of lapping each punch pin receiving aperture to fit the individual pin. Manifestly, thepresent invention reduces the number of manufacturing steps involved in making a punch block assembly .and greatly decreases. the manufacturing cost-thereof.

'It will be understood .that the above-described embodiment is merely representative of vtheinstant inventionand that many variations may be made therein without departing firom the spirit and'scopeaof the-present invention. 7

What is claimed is:

7 the punch pins intermediate said opposed side wall-s to a 1. A punch block comprising a member of U-shaped cross-section composed of onematerial and having a pair -of legs and a base, a plurality of projections on the extremities of said legs forming therebetweentar plu-.

rality of longitudinally-aligned receiving slots having bearing surfaces thereon, a plurality of slidable punch pins of greater len gththan thedistance between the legs and of a diameter less than thelength of' said-projections, said pins being disposed in said-receiving slots, and being I guided by said bear-ing surfaces, and a member composed of a resinous plastic material disposed between said legs and -base of said first-mentioned member-and'surrounding I each of said individual slidable punch pins to retain each of said punch pins against its respective bearing'surface.

2; A punch block assembly for punching intelligence bearing holes in a web of material, comprising a die plate having a plurality of punch pin receiving slots formed therein, a punch 'block composed of a first material having 'a base and a pair of legs defining a cavity with said base, a plurality of projections at the edges of said legs, each adjacent pair of projections having therebetween longitudinally aligned bearing surfaces, a plurality of pins laid on said bearing surfaces in slidable engagement therewith and spanning said cavity, and a retaining and guiding member composed of a plastic material extending from said base of said block vto surround the pins to re- 7 tain each of said pins against its respective bearing surfaces and to guide the portions of the pinsgintermediate said-'bearing surfaces on said legs.

3. A punch block assembly comprising a block of metallic material having a cavity defined by surrounding--.

walls, at least one of said walls having'an irregularity therein, a plurality of projections at the edges of certain of the walls forming therebetween a plurality of longitudinally aligned slots having 'bearing surfaces thereon between said projections, a plurality of slidable punch pins of greater length than the distance between said certain of the wal'lstdisposed in said slots andengaging said bearing surfaces to span the space between said certain, walls, and a retaining and guiding rnember composedof a resinous plastic material filling and surrounding said irregularity in said side wall to anchor saidretaining and guiding means in said cavity and surrounding each of said individual pins to retain each of said pins against its respective bearing surface and guiding the portion of the pins intermediate said certain-of the walls. 4. A punch block assembly comprising a unitarymetallic block having a cavity formed therein, said block having apluralityof lmigitudinally aligned slots formed in opposed side walls of said block, said slots having bearing surfaces thereon, a plurality of punch pins supported 7 for slidable movement in saidslots, and-:a punch pin retain-ing and guiding means of resinous material cast-,

in situ, in said cavityand surrounding the portions of retain each of said punch pins against its respective bear-ing surfaces, and guiding said punch pins' during their 7 movements. 3

References --Cited.in the ,file of this patent UNITED STATES PATENTS.

Switzerland June 1, 

1. A PUNCH BLOCK COMPRISING A MEMBER OF U-SHAPED CROSS-SECTION COMPOSED OF ONE MATERIAL AND HAVING A PAIR OF LEGS AND A BASE, A PLURALITY OF PROJECTIONS ON THE EXTREMITIES OF SAID LEGS FORMING THEREBETWEEN A PLURALITY OF LONGITUDINALLY ALIGNED RECEIVING SLOTS HAVING BEARING SURFACES THEREON, A PLURALITY OF SLIDABLE PUNCH PINS OF GREATER LENGTH THAN THE DISTANCE BETWEEN THE LEGS AND OF A DIAMETER LESS THAN THE LENGTH OF SAID PROJECTIONS, SAID PINS BEING DISPOSED IN SAID RECEIVING SLOTS, AND BEING GUIDED BY SAID BEARING SURFACES, AND A MEMBER COMPOSED OF A RESINOUS PLASTIC MATERIAL DISPOSED BETWEEN SAID LEGS AND BASE OF SAID FIRST-MENTIONED MEMBER AND SURROUNDING EACH OF SAID INDIVIDUAL SLIDABLE PUNCH PINS TO RETAIN EACH OF SAID PUNCH PINS AGAINST ITS RESPECTIVE BEARING SURFACE. 